You're spinning and striking with the forearm, palm inwards, using the movement of the whole body to power the attack.

Without a doubt one of the dumbest looking uses for that posture I have seen.

He is basically doing "peng" from "Grasp the swallows tail". You did Judo. Turn the uke around so that his left foot is forward and see how much more sense the app makes. Now, to make it make even more sense, adjust the positions of the hands on the guy in black so that either his right hand is either behind the other guys elbow or alternately placed behind the uke's neck or back.

If you do it like that then the lead leg of the guy in black is hooking or obstructing the lead leg of the uke while his arms are either locking out the other dude's lead elbow or simply hooking is neck in conjunction with the rotation to the right. Then it becomes a throw.

I'm not saying you can't back hand/arm the neck like that but if you want to see it as a striking maneuver then the whole posture has to change. I don't see any striking power in that pic.

".....Without a doubt one of the dumbest looking uses for that posture I have seen."

Yes, but don't you think that any method shown in a static pose tends to look "dumb".
In my own classes, its not at all unusual to show a technique and have one of the students comment that it would be easy to avoid or cancel the effectiveness of the technique. Invariably when I ask them to initiate the attack for themselves and make the necessary adjustments, they fail. I think this is one of those cases where "everything seems easier than it is" (3rd Cor. ; Murphy's Law). Thoughts?

If we are talking about the same type of technique in using the forearm (and I'm not sure from the description), then it sounds like the element of "jai". Jai would not be a normal strike with impact, but more like a shove. There can also be an element of "an" (impact with palm) with the other hand.

With a little modification there can be elbow in there and the set up for some throws.